While most of the influences on the mechanical properties of particleboard appear to have been investigated, there is a lack of knowledge about the influence of particle size or particle dimensions due to the absence of a suitable particle measuring technique. The introduction of laser-based 3D scanning technology makes it possible to automatically determine the dimensions, surface area, and volume of particles. In this study, the influence of particle size on the mechanical properties of particleboards was investigated. To isolate potentially overlapping influences, single-layer particleboards with a uniform density profile were produced and analyzed. The amount of adhesive specific to the surface of the (fine) face layer particles and (coarse) core layer particles was adjusted utilizing 3D scanning of the surface areas to ensure comparability despite changes in particle size. It was found that with increasing particle size, the modulus of rupture (MOR) and modulus of elasticity (MOE) increase, while the internal bond strength (IB) decreases. It is considered whether these effects result from a particle-size-dependent orientation of the particles in the board. Furthermore, it is shown that all the aforementioned properties increase with increasing surface-specific adhesive amounts. Examples are provided to demonstrate how such fundamental relationships can be utilized to enhance the particleboard production process.

Particleboard properties result from a variety of material and process-related parameters. While many of them have been extensively investigated, there is a notable lack of knowledge regarding the influence of the particle geometry. This is due to a longstanding lack of suitable measurement technologies and, in the investigation, unintentional overlapping of other interference factors. In the present study, the influence of particle size and surface-specific adhesive amount (SSAA) on the formation of particleboard properties was investigated. Laser-based 3D scanning technology was used to determine the dimensions and the specific particle surface area of particles of different sieve fractions, from which different types of boards were produced. This approach allowed the SSAA to either be maintained at a constant level for boards made from different sieve fractions (influence of particle size) or to be specifically adjusted for boards made from a single fraction (influence of SSAA). To further isolate the influence of particle size and SSAA from the interfering influences of an uneven distribution of particles of different size, adhesive and density, the boards were produced with a single-layer structure and a homogenous density profile. As particle size increased, a statistically significant reduction (all statistical tests were carried out at a significance level of α = 0.05) in modulus of rupture (MOR), modulus of elasticity (MOE) and internal bond strength (IB) was observed, accompanied by an also statistically significant increase in thickness swelling (TS) and water absorption (WA). As the SSAA increased, the MOR, MOE and IB showed a corresponding statistically significant rise, while TS and WA significantly decreased. This knowledge of basic coherences (since significant interference factors were excluded) provides the basis for targeted process optimization in the production of particleboards.

Replacing greenhouse gas-intensive building materials with wood products from sustainable forestry contributes to the implementation of current climate conventions such as the Paris Agreement. Hardwood products, such as laminated veneer lumber made of beech (e.g., BauBuche), are an alternative to conventional building materials. For the application of wood products in the construction sector, a precise knowledge of the mechanical and physical properties is essential. Therefore, the aim of the present study was to investigate the sorption behavior and associated dimensional changes of the product BauBuche. This was done by applying a manual testing procedure (climatic chamber, balance and caliper) as well as a dynamic vapor sorption analyzer equipped with a camera. During initial moistening after production, due to the irreversible spring back (approximately 2 mm at 50 mm; i.e., 4%), Baubuche shows an extremely strong swelling in the radial direction. Once the maximum spring back is reached, Baubuche shows sorption behavior in the radial and tangential direction, which is comparable to that of solid beech wood in the radial direction. Consequently, the dimensional changes caused by moisture changes must be taken into account in the dimensioning of Baubuche components in order to avoid damage to building structures.

Wood and its processing into particles are, combined, the largest cost factor in the production of particleboard, followed by the cost of adhesive. Thus, reducing their cost is a goal of process optimization. This study investigated whether possible savings could be identified and quantified by determining the particle surface using automated three-dimensional laser-scanning technology (3D Particleview, Fagus-Grecon). The focus was on saving adhesive by sieving out adhesive-consuming fines. It was shown that, currently, with the actual prices for wood (89 €/t), particle preparation (37 €/t), and adhesive (570 €/t), the resulting additional costs for particles are overcompensated by the savings for adhesive with high adhesive content (e.g., 19%). The assumption of uniform distribution of adhesive on the total surface of all particles was checked for correctness using digital reflected light microscopy (VHX-5000, Keyence). Since urea-formaldehyde (UF) adhesive commonly used in particleboard production can only be detected with increased effort, phenol-formaldehyde (PF) adhesive was applied for the tests. Ultraviolet microspectrophotometry (UMSP) was used to rule out excessive penetration of the adhesive into the wooden tissue of the particles. The examination of the distribution of the adhesive over the surface showed that smaller particle sizes tended to be more heavily coated with adhesive. This means that the calculated savings still underestimate the real-life potential or that potential savings exist even with lower adhesive prices or higher prices for wood.

An irreversible swelling was detected in laminated beech veneer lumber within the initial moistening. Supported by the facts that the lay-up of the glued veneers is exposed to high pressure during hot pressing, and that the density of the finished material exceeds that of solid beech, it was hypothesised that the wood substance is compressed. Laboratory X-ray density profile scans were performed to check this and to identify the part of the material cross section in which the densification has taken place. The higher density was found to be located in the area of the adhesive joints, uniformly over the cross section, while the density in the middle of the veneers corresponds to that of solid beech wood.